Diggin It
Super Star Member
How long is the galvanized duct? Attach with screws? Do you flatten the duct to match the shape of the 4X4s or just leave it cylindrical?
Standard 24" length available at Big Box stores. Stock 7" diameter provides clearance around a 4x4. Used 3" roof metal screws on each of the four sides of the timbers (arrows). Added short pieces of 1/2" PVC pipe as standoffs/spacers for each screw. Theiving little acrobats found that they could stand on another's shoulders and get over the first 24" piece, so I had to add another piece above it.

I was afraid I'd have an issue with wasps or spiders nesting inside, but so far that hasn't happened.